1. Field of the Invention
The present invention relates to the manufacture of tires. More precisely, it relates to the laying down of cords to build up a tire reinforcement. More particularly, it proposes means suitable for manufacturing such a reinforcement on a form close to or identical to the shape of the internal tire cavity, i.e., a substantially toroidal shape, supporting the blank of a tire during its manufacture.
2. Description of the Related Art
In this technical field, methods and apparatuses are already known for integrating the manufacture of tire reinforcements with the assembly of the tire itself. This means that, rather than having recourse to semi-finished products, such as reinforcement plies, one or more reinforcements are created in situ while the tire is being manufactured, starting from a spool of cord. Amongst these methods and apparatuses, the solution described in U.S. Pat. No. 6,463,978 B2, which is incorporated herein by reference (and which is a counterpart to patent application EP 1 122 057), is well adapted to the formation of carcass reinforcements on a rigid core, whose outer surface corresponds substantially to the shape of the internal cavity of the finished tire. This comprises apparatuses in which the cord, configured to build up a carcass reinforcement, is laid down in adjacent hoops over a rigid core by a mechanism having at least two arms arranged in cascade. The arms perform a reciprocating movement around the core, so as to place one hoop at a time with each outward motion and one hoop with each return motion, with the intervention of suitable pressers to apply the ends of the hoops one by one to the rigid core. The core will have been coated in advance with uncured rubber according to the architecture of the tire to be manufactured, which has the advantageous property of making it possible to adhere the hoops sufficiently and to hold them in place at least for the purposes of manufacture.
The laying down of cords on the core is all the more precise in that the eyelet through which the cord passes comes as close as possible to the core while laying down the cord. In certain embodiments of this invention, one is led to add at least a third arm in order to get closer to the core in the region of the base of the bead.